RESUMEN
An experiment was conducted in the fields of state Board of Agric. Research, during fall seasons in 2000 and 2001. The objective was to estimate the ability of improving F2 and F3 seeds of maize hybrids. The single cross hybrid Shahed [844 x 834] with its inbreds, Fl and F2 plants were used. In the first season, crosses were done between the plants of Fl and F2 generations as female parents and inbred lines 834 and 844 as male parents. In the second season variatal trial for 8 genotypes was carried out using a randomized complete block design, with three replications. The single cross hybrid was superior to both parents with positive heterosis for all the characters. The results showed that crossing Fl and F2 plants with the parent 834 decreased inbreeding depression more than the parent 844, in all the traits. This indicates that the effect of crosses difference was due to the genotype of the parent, high heterosis [14.6, 4.5, 15.7, 21.4, 7.1 and 33.6%] and low inbreeding depression [3.0, 5.4, 1.8, 3.0 and 8.3%] for the characters, ear length, number of rows/ ear, number of grains/ row, grain weight, number of grains/ ear and grain yield [kg/ ha.], occurred in the Fl and the crosses of [Fl x 834], respectively. It was concluded that crossing of Fl plants with the best parent, [of higher combining ability] reduced inbreeding depression